Enclosed internally heated electric discharge lamp luminaire for variable temperature service



Sept. 9, 1952 A. A. BRAINERD 2,610,289

ENCLOSED INTERNAL-LY HEATED. ELECTRIC DISCHARGE LAMP LUMINAIRE FOR VARIABLE TEMPERATURE SERVICE Filed Feb. 25, 1949 3 Sheets-Sheet l A TTORNEYS.

BRAIN ERD" Sept. 9, 1952 I A ENCLOSED INTERNALLY HEATED ELECTRIC DISCHARGE LAMP LUMINAIRE FOR VARIABLE TEMPERATURE SERVICE 3 Sheets-Sheet 2 Filed Feb. 25, 1949 INVENIOR: 1 157271112 flfirameni,

BY ATTORNEYS.

Sept. 9, 1952 A. A. BRAINERD 2,610,289 ENCLOSED INEERNALLY HEATED ELECTRIC DISCHARGE LAMP LUMINAI E FOR VARIABLE TEMPERATURE SERVICE Filed Feb. 25, 1949 s Sheets-Sheet s FIG:

ATTORNEYS.

Patented Sept. 9, 1952 UNlTEDff S-TATES PATENT;

ENCLOSED INTERNALLY HEATED ELECTRIC DISCHARGE LAMP LUMINAIRE FOR VARI- ABLE TEMPERATURE SERVICE Arthur A. Brainerd, Norwood, Pa.

Application February 23, 1949, Serial No. 77,956

particularly to gaseous dischargeioutdoor-lighting luminaires embodying means for maintaining eflicient operation through a wide outdoor ambient temperature'range. t

In the lighting art it is well known that the eiiiciency of gaseous discharge'lamps is considerably higher under optimum temperature conditions than the efficiency of incandescent lamps of the same wattage. Gaseous discharge lamps have therefore gone into extensive use in factories, omce buildings and the like. For indoor lighting where'the temperature of the air. surrounding the lamp is normallyof the order of 70 F. the light efliciency of such lamps has been very satisfactoryand their average life has been very high. However,their use for street lighting and other outdoor lighting applications has been limited by V the fact that there .is a substantial decrease in the light efiiciency of suchlamps at temperatures below about .60" F. Consequently such lamps have notgone into wide use for outdoor lighting since it has not been possible to provide an efiicient unit which is capable of furnishing alight output reasonably constant over the normaloivariations in outdoor temperatures. The presentinvention is directedv toward providing an outdoor lighting unit which utilizes a gaseous discharge tube and which efiiciently provides a substantially constant light output throughout a range of widely varying ambient temperatures.

A further difliculty heretofore involved in the use of gaseous discharge lamps for street lighting and the like arises out of the fact that the high voltage lines in general. use for? street lighting operate at 2300 volts or 4000 volts whereas the street lighting lamps commonly used operate at a much lower voltage. This has required the use of constant current transformers or other special transformer equipment in order toreduce such high voltages to the lower voltages required for the low voltage lighting-units heretofore employed. The use of such transformers adds materially to the expense and creates installation problems since it is customary to mount such transformers independently of the lighting unit. Therefore, one object of the present invention is to provide an efficient gaseous discharge. luminaire for outdoor :use utilizing voltages of the order of 2300 volts to 4000 volts at the luminaire terminals. I Y

It is a further object of my invention to provide a low-cost gaseous discharge outdoor lighting luminaire suitable for street lighting and the like. 1

. A further object of my invention is to. provide a gaseous discharge lamp luminaire. having. efficientlighting characteristics over a wide ambient temperature ranges 9 i.

Claims. (Cl. 24011.4)

A further object is to provide a gaseous discharge tube luminaire of the above described characteristics which may be efliciently operated over a wide ambient temperature range when connected directly across a high voltage'source and which will provideadequate light for time periods of the order ofone year without lamp replacement.

A still further object of the present invention is to provide an enclosed luminaire for outdoor use. having means within said luminaire for creating and maintaining an inside air temperature at the lamp location sufliciently high to insure efficient and stable operation of a gaseous discharge tube over a wide range of outdoor temperatures. 1

The broad objectives of the present invention are achieved by providing within the lamp enclosure a current limiting and heat producing reactor in circuit with the lamp and continuously operative during the period of operation ofthelamp. A v,

Other objectives are achieved in the device of the present invention by automatically combining theaction .ofa plurality of factors all of which are varied in response to changes in the outside ambient temperature. In order to employ high voltages at the luminaire terminals, I provide a suitable reactor which is connected in circuit with the gaseous discharge tube and the line and which is mounted inside the luminaire enclosure below and in heat exchange re-' lationship with the air surrounding the gaseous discharge tube so that the reactor adds heat to the lamp area of the enclosure when the lamp is operating. At the same time the luminaire and the reactor are so constructed and arranged as to provide an air space which undergoes changes in temperature responsive to changes in' the outside ambient temperature but is not affected by the added heat derived from the reactor. I have also provided means for automatically increasing the heat output from the reactor and at the same time increasing the current to the lighting tube when the outdoor 1 minimum. 1 7

The foregoing and, other objects are attained by my inventive device disclosed. hereinand il-. lustrated in the appended drawings, in which:

Fig. 1 is a representation of the'external appearance of the luminaire of the present invention mounted on the usualv pole. l

V, Fig. 2 is a sideviewof the luminairepf Fig. 1 partly in section to show details of the cap member. .3 J .j

Fig. 3 is avertical section through the luminaire of Fig. 2 taken, along the lines III-III of Fig. 4. Fig. 4 is 'a transverse vertical section through ambient temperature falls below a predetermined by the arrows 'V-V of Fig. 2.

Fig. 6 is a plan view of an alternate form of the invention.

Fig. 7 is a vertical section takenalong the lines VIIVII of Fig. 6.

Fig. 8 is a vertical section taken along the lines VIII-VIII of Fig. 7.

Fig. 9 i a circuit diagram of the electrical components of one embodiment of the present invention. I

Fig. 10 is a circuit diagram showing the electrical components of an alternate form of the present invention;

According to my invention, a gaseous discharge lighting tube I is mounted in an enclosure .6, as shown .in 5, together with certain auxiliary electrical equipment hereinafter described includinga reactor 1 which is so constructed as to make it possible to operate the tube I directly from a high voltage source. The heat resulting from the power loss of the reactor 1 is added to the air surrounding the tube I. .The reactor. I is so constructed and arranged that its heat output is automatically increased through the action of thermostatic switch Ill when the temperature falls below a predetermined value. At the same time an increased current is applied to the tube I.

In Fig. 1 the enclosure 6, having an end .cap member 33, is shown attached to a standard pole by means of mounting arms 30 and 3|. High voltage leads I1 and are shown connected directly to the luminaire terminals. Clamps 32 are provided for attaching a transparent and nonheatconducting section which formsithe bottom half of enclosure 6. Details relating to the mounting elements and SI, the clamps 32, and the end cap 33 are shownin Figs. 2 and 4.

Referring now to Figs. 3, 4 and 5, a U-shaped gaseous discharge tube I is supported at its closed end by the bracket-,1. The extremitiesat'the open end of tube I are supported in sockets 3 and 4 which are held in place by means of a bracket 5. Reactor I consisting of a coil of insulated'wire wound around a laminated iron core is supported by hangers 8 and 9 which are attached to the upper half of housing 6 as shown in Fig. 4.

Thermostatic switch It; is mounted beneath the casing of reactor '1 and is thermally insulated from reactor I by the insulating strip I i. Switch I [I is responsivetochanges in the outside air temperature since' the air within the lower portion of the enclosure below the reactor. I is substantially at'the temperature of the outside air. A. bimetallic strip-type switch It comprising a" pair of. strips of metals having different coeiiicients of thermal expansion is shown, but it will be apparent that many of the commercially available thermostatic switches will be applicable in my inventive luminaire. The reactor I is provided with electrical contacts I2, I3 and I4 and switch I0 is provided with electrical contacts I5 and'IB in order to facilitate the completion of electrical connections in accordance with the diagram shown in Fig. 9.

In the operation of the circuit of Fig. 9 at relatively high outside air temperatures, switch II is open andthe' current flows through conductor I1, tube I, conductor I8, reactor 1 and conductors I9 and 2B, the entire body of the reactor I being utilized. When the temperature. at the location of thermostatic switch Illdrops below. a preselected value the. switch II} closes and the current flows through conductor I'I, tube I, conductor I8, the portion a of reactor 7, conductor 2|,

switch I0, and conductors 2.2 and {210, The closing of switch! increases the loss in reactor 1 and this results in an increased supply of heat to the air above reactor 1 and particularly the air surrounding tube I. At the same time the current input to'tube I is' increased and this increases the light output and also the heat generated by tube I. Since reactor I is mounted under tube I and is insulated from below, the increased heat output raises thetemperature oi the air surrounding the tube I to the desired operating temperature, without, however, raising the temperature of the air surrounding the switch I9.

In the operationof the alternate iormpf the present invention as illustrated in the dia ram of Fig; 10, the closing of switch 1.8 results :iuiconnecting resistance 50 across the portion fc of reactor I. This provides an overall increased power loss and hence an increasejin the heat supplied to the air surrounding tube 119m the combination of reactor 1 and resistance :59,

In Figs. 6, '7 ands an alternate'form of my invention is shown in which enclosure .40 is supported by a single arm III. 'Ligliting tube 52 mounted within enclosure Allandis DohStHmIQd and arranged to form a series .of three -.u..-shan lighting elements disposed one. above the other. Tube 42 is held in place. by bracket 143. and by sockets 4d and 4.5. Bracket 46' towhioh'sockets M and are attached is supported .on'the inner; wall of enclosure All by meansof iugs 14.1 and $8 whichare welded or otherwise integrated'with the enclosure wall. The lower hal-f oflenclosurexfl consists of a transparent and nor-hheatconduct ing cover 4.9 which isinounted'on hinge elements 50 and SI and is'held' inoperatingpositioni by the hasp 52. For. inspecting and servicing the cover as can be lowered to the position shown in dotted lines in Fig. '7. Reactor 1 is heldin'position uni derneath the lower-most levelfof tube il2iby straps 53 and 54 which are attached to theenclosure 4.! as shown in Fig.8. Thermostatic-"switch I! is mounted beneath the casing .of reactor 1 and is thermally insulated from'reactor'ilby the insulating strip II. Electrical contacts. I2," I3, Ill, I5 and I6 are provided to facilitate thezco'mpletion of electrical connections inaccordance with the diagram of Fig. 9'

Asshown in Fig. 1, theiluminaireiof myinven-L tion may be connected directly across;a high voltage line at voltages as high. assets-1.01: .4600 volts or. above. The electrical connections within the enclosure will beapparent. fromtthe diagrams of Figs. 9 and 10 and it will be apparent that the. leads to lines I1. and iofcan be. brought out through the wall of the "enclosure. in ways. well iznown in the art.

Structurally, my invention is adaptedto various designs. The lower "surface of the enclosuredis made of atranspare'nt or translucent material such as glass, plastic or the like} Thetr ansparent housing member is shaped't'o fit snugly-with the upperh'al'f of enclosure 8- and tlisop'erates' 'to minimize heat lossesat this reveren -ti e the material of enclosure tast ngs-caden e ofgheat the air in the lowermost portion remains substantially at the temperature of ttejeutsme air. For application in unusually cold climates the upperhousing may be insulated. The entire housingunit of. Fig. '1 is preferably openat .oneiend and provided with a snug-fitting cap '33.wl'1ich isslide ably removable for rapid replacement :or. ino'perev ative parts. A slight displacementtioftthelight:

mg-tube toward the open end of the luminaire disconnects the tube from its sockets and opens Example 1 A street lighting luminaire was designed following the embodiment shown in Figs. 2-5 :for operation'at 2300 volts. The discharge tube was 8 feet long and one inch in diameter and was equivalent to a resistance of 2000 ohms. A reactor 1 having an impedance of 12,000 ohms at 3.7% power factor was positioned as shown in Fig; 3 and wired according .to Fig. 9, conductor 2| beingconnected to reactor 1 in such position that the-portion a of reactor 1 included 90% v of reactor 1. At an applied line voltage of 2300 Example 2 The lamp described in Example 1 Was designed following the wiring diagram of Fig. 10 for operation at a voltage of 2300 volts across the terminals. Reactor 1 was of the same type as in Example 1 but had an overall impedance of 11,500 ohms. Resistance '50 had a value of 600 ohms. With the bimetallic switch I0 in its open position the current flow was 200 milliamperes and the power losses were 7 9 watts in the lamp and 17 watts in the reactor, or a total of 96 watts. After closure of switch [0 the current increases to 210 milliamperes and the losses amount to about 87 watts in the lamp, 17 watts in the reactor and 20 watts combined loss in the resistor and 10 of the reactor. The total power loss was therefore 124 watts or an increased power loss of 28 watts on closing of switch ID with a corresponding heat loss available for heating the air surrounding the lamp.

While I have described the present invention in terms of a reactor having certain specified characteristics, it should be noted that changes in the construction of such reactor may be made if it is desired to provide more added heat or less added heat. For instance, changes in the windings or in the core of such reactor will result in changes in the heat losses and these changes may be made taking into account the anticipated variations in outside ambient temperature. It is also possible to provide a reactor which is adjustable to give a suitable current loss and at the same time provide a quantity of added heat properly correlated with anticipated variations in outside ambient temperatures.

While the drawings in the present application include a thermostatic switch in for changing the amount of heat loss in reactor 1, it will be understood that for many conditions of operation improved results in lamp operating efficiency will be obtained through the practice of the present invention even where such switch is omitted. For

instance, in the latitude of Philadelphia I have found that the loss in efficiency caused by heating the air surrounding the lamp to a temperature in excess of the optimum is more than offset by. the gaininefficiency resulting from the addition of heat duringperiods when the outside air temperature is below. the optimum with respect tclamp efficiency andtherefore a net gain inflefiiciency is obtained even where the heat lossatthe reactor remains constant.

Having thus'described my invention, I claim:

' :1; In anaoutdoo'r street lighting luminaire, having 'an:- enclosure, a gaseous discharge lamp mounted insaid enclosure, a current limiting reactor also in said enclosure,'said reactor having substantial heat loss on 'energization, said lamp being Wholly above said reactor, with substantially uninterrupted free space therebetween, an electric circuit connecting the reactor and discharge lamp together and energizing the reactor to furnish heat continuously to the luminaire by upward air convection within the enclosure throughout the entire period of operation of the lamp, and a thermostatic switch mounted below and thermally insulated from said reactor, said switch being disposed near thebottom of the enclosure for response to fluctuations in ambient temperature, and also being connected in circuit with said reactor and effective to remove from the circuit a portion of the reactance element, thereby increasing the heat loss of the reactor, and of the discharge lamp itself, in response to decrease of ambient temperature below a predetermined value.

2. An electric discharge lamp luminaire comprising an enclosure, an electric discharge lamp mounted in said enclosure, a reactor coil mounted in said enclosure wholly below the horizontal plane tangential to the bottom of said lamp, with substantially unobstructed free space therebetween, a thermostatic switch mounted adjacent the bottom of said enclosure for response to changes of temperature outside the enclosure. thermal insulating means intermediate said reactor coil and said thermostatic switch, a source of electricity, a lamp-operating circuit including electric conductors connecting saidsource, directly to the reactor coil and directly to the discharge lamp, and connecting the reactorcoil in series with the discharge lamp, and by-pass conductors connecting said thermostatic switch into said lamp-operating circuit through a portion only of said reactor.

3. An electric discharge lamp luminaire comprising an elongate shell closed at one end and open at the other end, electric sockets spaced apart within the shell adjacent said closed end, an electric discharge lamp in the form of an elongate U-tube having free ends spaced according to the spacing of said sockets and adapted to be inserted therein, said U-tube extending lengthwise of said elongate shell with its closed end accessible at the open end of said elongate shell remote from said sockets, an electrically energized heating element in said enclosure connected in circuit with said U-tube, a thermostatic switch mounted adjacent the bottom of said elongate shell for response to changes of temperature outside of the shell, said thermostatic switch being connected in circuit with said heating element to control the heat loss thereof, and a removable cap element shaped to fit the open end of said elongate shell to form an air-tight enclosure, said removable cap normally confining heat within said shell, and said U-tube being readily removable through the open end of said shell by removing said cap and gripping the closed end of the U-tube.

4. An electric discharge lamp luminaire, com prising an elongate shell closed at one end and open at the other end, electric sockets spaced apart within the shell adjacent said closed end, an electric discharge lamp in the form of an elongate U-tube having a. pair of legs having free ends spaced according to the spacing of said sockets and adapted to be inserted therein, said U"-t.ube extending lengthwise ofsaid elongate shell with its closed end accessible at the open end of said elongate shell remote from said sockets, and said legsv being at, substantially the same: level, an electrically energized heating element in said en.- closure connected in circuit with said U-itubasaid heating element being between. and wholly below the horizontal plane tangential to the bottomv of said legs with substantially unobstructed free space betweenv the heating element. and each of said legs, and a removable cap element: shaped to fit the open end of said elongate shell toform an air-tight enclosure, said removable can normally confining heat within saidshell, and said U-tube 25 Number being readily removable through the open end of said shell by removing said cap and gripping the closed end of the U-tube'.

5. The invention set forth in claim 1 further characterized by the fact that the lower portion of the luminaire enclosure is constructed of light transmitting material having low thermal conductivity.

ARTHUR A. BRAINERD.

REFERENCES GITED UNITED STATES PATENTS Number Name Date 1,988,555 Harse Jan. 22, 1935 2,101,135 Finch et al.. n Dec. 7, 1937 2,167,472 Bed'ford July 25,. 1939 2,194,300 Found 19, 1940 2,203,550 Spanner June 4, 1940 2,293,116 Claspy Aug; 18, 1942 2,302,667 Duncan -1 Nov. 24, 19.42 2,373,402 Lecorguillier Apr, 10, 1945 2,456,870 Francis et a1 Dec. 21, 1948 FOREIGN PATENTS Country Date 392,796 Great Britain May 25, 1933 

